Process of hot water aging of wool treated with an anti-felting agent



PROCESS OF HOT WATER AGING OF WOOL TREATED WITH AN ANTIFELTING AGENT Filed March 11, 1966 March 4, 1969 o. c. BACON ETAL 3,431,132

INVENTORS OSBORNE COSTER BACON SAMUEL BECK CUPP ATTORNEY United States Patent 3,431,132 PROCESS OF HOT WATER AGING OF WOOL TREATED WITH AN AN TI-FELTING AGENT Osborne C. Bacon, Pennsville, N.J., and Samuel B. Cupp, Wilmington, DeL, assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Mar. 11, 1966, Ser. No. 533,722 U.S. Cl. 1177 Int. Cl. D06m 3/02; C08g 17/00 2 Claims ABSTRACT OF THE DISCLOSURE The present invention is directed to a process of finishing wool to impart resistance to felting and to gain other significant advantages. More particularly, this process involves the fixing of a polymeric acid chloride surface modifying agent on the surface of wool fiber by bringing wool which has been treated with the agent in solvent solution into contact with hot water.

Heretofore, textile mill practice has been to apply a solvent solution of the surface modifying agent, to remove the solvent in hot air or on hot can dryers, and to continue the heating of the dried fabric in air or on the dryers to fix the agent on the fiber against removal by subsequent laundering, in effect, to cure the treated fiber. Hot cylinders have been mostly used for drying and curing with resultant heavy accumulation of the agent on the surfaces thereof, even when the cylinders were coated with a non-adhesive tetrafluoroethylene resin or covered with terephthalate ester film. Such deposits necessitate shutdowns for cleaning which restrict production. In such a finishing procedure, the potential relaxation shrinkage is not all removed. This is the shrinkage that occurs by thoroughly wetting a fabric with water without mechanical action and drying in the absence of tension. Another difficulty is that a heat-cured fabric tends to be stiff and exhibit poor hand as a result of interfiber bonding. In addition, solvent recovery from hot air dryers is costly.

It is, therefore, an object of this invention to provide a novelmethod for treating wool to render it resistant to felting. Another object is to provide a practical, economical process for rendering wool resistant to shrinkage from relaxation, compaction, and felting during machine washing. A still further object is to provide an improved process for fixing a surface modifying agent on the surface of wool.

These and other objects of the invention will become apparent from the following description and claims.

In the Textile Research Journal, vol. 34, November 1964, pp. 939-944, D. E. Remy et al. of the US. Govt. Western Regional Research Laboratory report a study of the properties and applications to wool to Du Ponts 3,431,132 Patented Mar. 4, 1969 preferred Surlyn T felting resistant agent. The polymer was applied to the wool in an organic solvent by padding and cured in a forced-air oven at C.

In the same journal, December 1964, pp. 1105-07, the same authors report on a new method for textile finishing which involves the use of (l) a Du Pont felting resistant agent and (2) a diamine fixative. Wool flannel is immersed successively in dilute solutions of these reactants, lightly washed in dilute detergent solution, rinsed in water, and dried. The need for subsequent curing is said to be eliminated by the phase boundary cross-linking that is obtained. In neither article is there a disclosure of the hot water curing process of the present invention.

More specifically, the present invention is directed to a process of treating wool fiber to achieve resistance to felting which consists essentially of 1) applying to said wool from about 0.5% to about 5.0% on the weight of the dry fiber of an acid chloride-containing polymeric shrink-proofing agent dissolved in an inert solvent having no reactive hydrogen, (2) contacting the thus treated wool fiber with water at F. to 212 F. for about 0.5 minute to about 10 minutes. An optional step (3) is one wherein the fiber is held under tension during the contact with hot water.

Advantages of the invention process The improved novel process of this invention offers many advantages over the known art of treating wool to render it resistant to felting. First, there is no build-up of the shrinkproofing agent on the surfaces of the drying equipment with attendant loss of material and shutdown for removal of the deposited material, since the impregnated fabric is freed of solvent and cured in a hot water bath. Second, fabric may be cured in the relaxed state in the hot water; in the presence of an organic solvent wool fails to relax. Third, fabric cured under tension in hot water does not later relax as does hot air-dried and cured fabric which is in a somewhat stretched condition before the treatment with the solution of the polymeric acid chloride. Water-cured fabric may be said to be set. Fourth, the hand of the hot water-cured fabric is more limp, particularly when cured slack, than the hot air-cured fabric. Fifth, for a subsequent dyeing operation the hot water-cured fabric provides a wet fabric that is substantially easier to dye than dry-cured fabric; the latter is difiicult to Wet out in a reel dyeing machine. Sixth, the invention process affords a considerable saving in cost of solvent recovery compared with hot airdrying and curing. A potential advantage is the possibility of increasing the yardage of fabric from a given number of square yards of goods before finishing. This attainment may require tension in both warp and filling directions. Under warp tension only, however, some constructions of fabric will stretch relatively more in the warp direction than they will contact in the filling direction.

Another significant advantage is that a significant increase in the rate of the amount of fabric that may be treated in a given unit of time is achieved.

Wool fiber Wool fibers which may be treated effectively according to the subject invention take the form of woven and knitted fabrics; fabricated garments such as shirts, dresses, sweaters, socks, and the like; yarns; fabric blends of wool and other fibers such as cotton, rayon, polyester and acrylic types; and tops.

Surface modifying copolymer The surface modifying agent employed in the present wool treating process as a shrink-proofing agent is a copolymer comprising 1) ethylenically unsaturated units having the formula:

where A is hydrogen, C to C alkyl, C to C alkoxy, aryl, chlorine, bromine, carboalkoxy such that the monomer is an acrylate or methacrylate, acyloxy such that the monomer is a vinyl ester, cyano, aldo such that the monomer is acrolein or substituted acrolein and B is hydrogen, methyl, chlorine or bromine and (2) alpha, beta-ethylenically unsaturated carboxylic acid chloride units having 3 to 8 carbon atoms. The alpha, betaethylenically unsaturated carboxylic acid chloride units are present in the copolymer to the extent of at least 0.1 mole percent and can be as high as 50 mole percent. The preferred concentration of the acid chloride component of the copolymer is from 0.2 to 20 mole percent. The ethylenically unsaturated units of the copolymer may be supplied by a single monomer or at least by two different monomers and such units will be present in the copolymer in the amount of at least 50 mole percent based upon the total moles of units polymerized to form the copolymer. The degree of polymerization of the acid chloride copolymer should be at least 75 to 100 to ensure that the copolymer is a solid at use temperatures which are usually below 125 F.

Direct polymerization of ethylenically unsaturated acid chlorides does not result in the formation of polymeric materials which are suitable for use as shrinkage resistant agents in the invention process. The acid chloride groups in the polymeric agent are obtained by the polymerization of an alpha, beta-ethylenically unsaturated acid containing preferably 3 to 8 carbon atoms which is then converted to the acid chloride. Examples of such acids are acrylic, methacrylic, itaconic, maleic, crotonic, fumaric, glutaconic, and cinnamic acid. In the case of the polycarboxylic acids, one of the acid groups can be esterified.

The preferred monomers for supplying the ethylenically unsaturated units of the copolymers are alpha olefins such as ethylene, propylene, l-butene, l-pentene, l-hexene, 4-methyl-1-butene, styrene, and the like. The scope of the acid copolymers suitable for conversion to polymeric acid chloride for use in the invention process is illustrated by the following examples. Copolymers of ethylene/acrylic acid, ethylene/methacrylic acid, ethylene/itaconic acid, ethylene/methyl hydrogen maleate, ethylene/maleic acid, styrene/methacrylic acid, methyl methacrylate/methacrylic acid, ethylene/acrylic acid/ methyl methacrylate, ethylene/methacrylic acid/ethyl acrylate, ethylene/itaconic acid/methyl methacrylate, ethylene/methyl hydrogen maleate/ethyl acrylate, ethylene/methacrylic acid/vinyl acetate, ethylene/propylene/ acrylic acid, ethylene/styrene/acrylic acid, ethylene/ methacrylic acid/acrylonitrile and ethylene/vinyl chloride/acrylic acid.

The preparation of the copolymers from which the acid chloride copolymers are derived is well known; for example, methods for the preparation of ethylene/carboxylic acid copolymers are given in U.S.P. 2,646,425. In general, the copolymers,are formed by direct copolymerization of the monomers employing a free radical catalyst, such as peroxide, or Friedel-Crafts and related ionic catalysts. The polymerization is generally carried out in the presence of an inert solvent but may also be carried out in bulk when the monomers are liquid at polymerization conditions. The acid chloride copolymers employed in the invention process are obtained from the acid copolymers by treating with a chlorinating agent such as carbonyl chloride, thionyl chloride, phosphorus trichloride, and phosphorus pentachloride. The chlorine substitution is usually carried out in an organic solvent for the copolymer, preferably a chlorine-containing solvent such as carbon tetrachloride, perchloroethylene, trichloroethylene. Although it is possible to have a quantitative conversion of the acid to the acid chloride, satisfactory products for use in the invention process are obtained at lower conversions.

The following statement sets forth a method for the conversion of an acid copolymer to the corresponding acid chloride product:

One pound of ethylene/vinyl acetate/methacrylic acid copolymer, 69.9 parts of ethylene per 23.2 parts of vinyl acetate per 6.9 parts of methacrylic acid having a melt index of 480, was added to 3 gallons of carbon tetrachloride at a temperature between 50 and 60 C. grams of phosphorous pentachloride was dissolved on a steam bath in 1 /2 gallons of carbon tetrachloride. This solution was added to the ethylene terpolymer slurry. The mixture was placed in a five gallon glass-lined stirred kettle fitted with a condenser and a nitrogen inlet. The temperature was maintained at 60 C. for two hours with agitation while a slow nitrogen purge was maintained on the kettle. Hydrogen chloride gas was trapped off from the reactor. The temperature was then raised to 70 C. for live hours. All polymer was in solution. The solution was then added to 30 gallons of acetone with vigorous stirring to precipitate the polymer. The polymer was collected on a filter, washed several times with acetone by redispersing the polymer in acetone and dried in a vacuum at room temperature. Complete conversion of acid to acid chloride was indicated by infrared scan, and no loss in vinyl acetate was detected. Polymer was readily soluble in xylene at room temperature. The melt index referred to is a measure of melt viscosity which defines the molecular weight. This index is described in detail in ASTMD1238-57T.

Solvent The solvent used to produce a solution of the polymeric acid chloride wool surface modifying agent is one having no reactive hydrogen atoms and preferably having a normal boiling point below the boiling point of Water or steam distilling at this temperature and being nonflammable. By steam distilling is meant a flashing off from the fiber of solvents having a B.P. below F.; the vaporizing, with steam, of solvents having a B.P. above 212 F.; and the flashing off or vaporizing, with steam, of solvents having a B.P. between 160 F. and 212 F., depending on said water temperature. Representatives of such a solvent are perchloroethylene, trichloroethylene, carbon tetrachloride, methyl chloroform.

Application of solution The solution of the copolymer containing acid chloride units is applied to woolen fiber 1) by padding wherein a dip into a solution bath is followed by passage through squeeze rolls, (2) by spraying one or both surfaces of the fabric, or (3) by dipping followed by centrifuging to remove the excess solution. The padding and spraying application methods may be operated continuously and are preferred for woven or knitted piece goods. The dipping and centrifuging procedure is suitable for sweaters, socks, yarns in skein form. The copolymer solution may also be applied in a package or raw-stock dyeing machine Where the solution is pumped through a package of yarn or raw-stock (loose fibers). In this case the solvent may be removed by suction and then hot water is pumped through the fibers to effect the cure. Alternatively, the impregnated fiber may be removed from the dyeing machine for the hot water-cure in another piece of equipment. The copolymer solution may be applied by electrostatic sprayinga method that may be preferred for non-uniformly shaped objects.

The wool fiber may be treated at any of several stages of processing, e.g. (1) fibers before spinning; (2) spun yarn; (3) fabric (a) after carbonizing, (b) after bleaching, (c) after dyeing, (d) before dyeing or (e) after printing; (4) knit fabrics, (5) knit garments and (6) sewn garments may also be so treated.

The amount of copolymer that is applied to the W001 fiber depends upon whether the fiber is to be made resistant to felting during such mill processing operations as bleaching, scouring, and dyeing or is to have resistance to felting during laundering. To prevent felting during one or two machine launderings a concentration of at least 1.2% o.w.f. of the polymeric acid chloride is required. To withstand 5 or more launderings Without felting a concentration of 1.8% to 2% o.w.f. is recommended. Amounts of up to 5% o.w.f. may be used in special cases where the tendency to felt is hard to overcome and the fabric hand and cost of application are secondary considerations. Felting of the fibers during mill processing is generally prevented with from 0.5% to 1% o.w.f. of the copolymer, but higher amounts will be used under severe conditions of wet processing. Enough solution of a given solution concentration is picked up by the fiber to provide the above amounts of shrink-proofing agent. A pickup of 100% to 150% by weight is usually attained.

Water curing bath The fiber impregnated with the acid chloride copolymer solution is then brought into contact with water at a temperature of 160 F. to 212 F. for from about 0.5 minute to 10 minutes to remove the solvent and to fix the copolymer on the fiber. The temperature and contact time conditions depend upon such factors as the boiling point of the solvent, the weight of fabric, and the amount of solution in the fibers. Excellent results are obtained in 30 seconds in a water bath at 212 F. when trichloroethylene is rapidly flashed from a light weight woolen fabric bearing initially its own weight of the solvent. Lower temperatures than 160 F. may be maintained, but longer times are required to drive off the solvent and the shrink-proofing may be reduced. Although the copolymer may be fixed on the fiber in less than 0.5 minute, 0.5 minute is the practical minimum time needed to achieve both a cure and solvent removal.

The pH of the hot water bath may vary from an acid range of pH 2-3 to an alkaline condition represented by pH 9-10. pH control is desirable to minimize the damage to wool caused by alkali at high temperatures, to reduce dye bleeding, and to prevent corrosion of metal parts of equipment. A buffer solution and corrosion inhibitors may be desirable in some cases.

Optional tension When tension is applied during the water cure the fabric is stretched over and above any stretch already in the fabric after previous aqueous processing and drying under tension. Tension applied during the cure will increase the area of the fabric if applied in both directions (warp and fill) and with some fabric constructions when applied warpwise only. The amount of tension applied will vary with the equipment used, speed of production, and width of the fabric. Tension may be measured in terms of the stretch obtained as measured after first marking a fabric, processing and remeasuriug. Stretching may be controlled in practice between zero and 10, 15, 20% or more. Tension may be controlled by the pull on the fabric required to move it through the machine and by back tension from the feed rolls. Filling tension can be applied by spreader bars or rolls or by a tenter frame.

FIGURE 1 of the accompanying drawing is a diagram illustrating the herein described and claimed invention hot water aging process for imparting felting resistance to W001. From a roll, 1, of untreated wool fabric, the fabric is drawn into the padding bath 2, for impregnation with the solution of the acid chloride-containing polymeric shrink-proofing agent. The padding bath is enclosed in box 3 to contain the solvent vapor and is fitted with squeeze rolls 4. From the padder the fabric is drawn into the hot water bath 5, usually steam heated and enclosed in cabinet 6 to contain the steam and solvent vapor. Although the diagram shows a hot water bath having only 4 upper and 5 lower rolls over which the fabric passes in its travel through the hot water, a series of such combinations of rolls may be used and the rate of travel of the fabric correspondingly increased. The solvent vaporized in the hot water bath is Withdrawn through the exhaust pipe 7 for recovery. The fabric as it leaves the hot water chamber is pulled through the drive and squeeze rolls 8 from where it is taken directly for further processing, such as dyeing, or is plated on a truck bed 9 in a cured semi-wet condition for transfer to another operation such as drying or dyeing, if not already dyed.

Representative examples further illustrating the invention follow.

Example 1 fabric were then cured (at) slack for 2 minutes at 250 F. after air drying, (b) slack for 2 minutes in boiling water, during which time the solvent was completely evaporated. The following fabric contractions were then measured.

Percent contraction based on cured fabric (warp and filling) Dry curing (9.) Wet curing (b) After cure After relaxation Then after 1 home type washing Then aiter 5 home type washings.

*The relaxation was obtained by wetting out thoroughly in wate containing a wetting agent and allowing the fabric to dry without tension.

Neither sample felted even after 5 washes. The 8% relaxation of the hot water cured portion of the fabric is noteworthy. The dry cured (a) fabric was difficult to relax or compact by washing; a condition that is undesirable since the fabric should be relaxed in the mill to prevent shrinkage during use by the customer. The hand of the dry cure was appreciably harsher and firmer than that of the wet cure.

In the same way, white wool flannel was impregnated to a pickup of a 2% solution in tetrachloroethylene of the following copolymers and cured slack for 2 minutes in boiling Water. The percent contraction after 1 home type washing is given in the table below.

While the control showed considerable felting, no felting occurred in the fabric treated with the first two copolymers. Some felting was evident in the fabric treated with the styrene copolymer, but then a significant resistance to felting had been imparted to the fabric.

Example 2 The procedure of Example 1 was repeated using a range PERCENT CONTRACTION (WARP AND FILLING) Cured 2 min. at 250 F. in hot air Loading o.w.f., in percent 1 1.2 1.4 1.6 1.8

After cure O 0 0 0 After relaxation 5. 3. 5 2. 4 1. 5 2. 5 Then after 1 home type washing 7. 0 4. 5 3. O 2. 0 3. 5 Then after 5 home type washings 13. 5 8. 0 6.0 5.0 6.5

Cured slack for 2 min. in boiling water Loading o.w.f., in percent 1 1.2 1.4 1.6 1.8

After cure 8 8 8 8 6. 5 After relaxation 9 8 8 8. 5 7. 5 Then after 1 home type wash... 8.5 8 8 8 8 Then after 5 home type washes 13 1. 0 10.5 9. 5 9.0

These results clearly show the greater degree of contraction in water than in air curing. The water cure, in effect, is setting the finish while the fabric is relaxed. The data also show that significant progressive shrinkage ceases at 1.2% concentration of the copolymer on the fabric for the water cure and at 1.4% for the dry cure.

Example 3 A white wool flannel fabric was padded to deposit its weight of a 1.5% solution of the first copolymer of Example 1 in trichloroethylene. Without drying, the fabric was immediately immersed:

(A) For 1 minute in boiling water containing 0.06%

acetic acid (B) For 1 minute in boiling water containing 0.06%

sodium bicarbonate (C) In boiling water for 0.5 to 5 minutes (D) In water at 180 F. for 1 minute (E) In water at 200 F. for 1 minute All treatments were air dried slack without heat and then given 5 home washes. None of the fabrics showed any evidence of felting.

Example 4 A white wool fabric was processed under tension in the warp direction by padding on 1.8% of the first copolymer of Example 1 from trichloroethylene and pulling it through a hot water bath (200 F.) over and under guide rolls and then over 5 hot cylinders heated to 250 F. The fabric emerged partly dry (about 50% water content). The time in the water was about 1 minute and the time on the hot cylinders was also 1 minute. These times do not take into account the time the fabric was out of the hot water going over the top guide rolls or the time the fabric was passing from one hot cylinder to the other.

The speed of the operation was 15 yards per minute. The

fabric was 55 inches wide before processing and 50.5

inches wide in the semi-wet state after processing. A yard mark made before processing measured 40.5 inches afterwards. These measurements indicate a stretch of 12.5% in the warp direction and a contraction of 8.2% in width.

The finished (dried) fabric was considerably limper than some of the same fabric processed by drying of the solvent on the same cans without the water cure. Shrinkage tests showed the following unusually high resistance to shrinking expressed in percent contraction of the fabric slack-dried after processing.

Percent After relaxation 0.6 Then after 1 home type wash 0.6 Then after 2 home type washes 2.5 Then after 3 home type washes 1.8 Then after 5 home type washes 2.6

The preceding representative examples may be varied within the scope of the present total specification disclosure as understood and practiced by one skilled in the art, to achieve essentially the same results.

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:

1. A process of imparting resistance to felting to wool fiber, which process consists essentially of the following steps:

(A) applying to said wool fiber from about 0.5% to about 5.0%, on the weight of the dry fiber, of an acid chloride-containing polymeric shrink-proofing agent, said agent being dissolved in a nonfiammable inert chlorinated solvent having no reactive hydrogen, and

'(B) contacting the wool fiber product of said step (A) with water at a temperature of from about F. to about 212 F. for about 0.5 minute to about 10 minutes.

2. A process according to claim 1 wherein the wool fiber contacted with water in said step (B) is held under tension during said contact with water.

References Cited UNITED STATES PATENTS 2,678,286 5/1954 Brunet et a1. 117-141 2,678,287 5/1954 Cupery et a1. 117-141 2,993,748 7/1961 Koenig 8l28 3,093,441 6/1963 Whitfield et al. 8l28 3,243,253 3/1966 Miller et a1. l17141 XR 3,266,931 8/1966 Zimmermann et a1. 117-141 XR 3,301,700 1/1967 Maloney 8l28 XR WILLIAM D. MARTIN, Primary Examiner.

H. J. GWINNELL, Assistant Examiner.

US. 01. X.R. 

